This invention relates in general to light weight vehicle wheels and in particular to a surface finish for a light weight vehicle wheel and a process for forming the surface finish.
Vehicle wheels include a circular wheel disc which can be formed across an is end of an annular wheel rim. Alternatively, the wheel disc can be recessed within the wheel rim. The wheel disc includes a wheel hub having a central pilot hole and a plurality of wheel stud holes formed therethrough for mounting the wheel upon a vehicle. Typically, the wheel disc also includes a plurality of wheel spokes connecting the wheel hub to the rim.
In the past, vehicle wheels have traditionally been fabricated by attaching a stamped steel disc to a rolled steel rim. Vehicle wheels also have been cast or forged from steel billets. Increasingly, vehicle wheels are being formed from light weight metals, such as aluminum, magnesium, titanium, or alloys thereof. Such light weight metal wheels can be cast or forged as a one-piece wheel or assembled by attaching a full or partial wheel disc to a wheel rim. Additionally, bimetal wheels can be assembled from a wheel disc and rim formed from dissimilar metals. For example, a cast aluminum alloy full face wheel disc can be welded to a partial wheel rim rolled from a strip of steel.
With all wheels, regardless of the material used to form the wheel, the outer surface of the wheel disc is visible when the wheel is mounted upon a car. Accordingly, the wheel disc can be formed having a pleasing aesthetic shape. The wheel disc outer surface is then typically machined to form a smooth surface which is subsequently provided with a surface finish which usually has a decorative high luster.
One type of surface finish, which is used extensively, is formed by chrome plating the outer surface of the wheel disc. During chrome plating, a layer of chromium, which can be polished to a high luster, is deposited upon the wheel surface. Known methods for forming a surface layer of chromium on a wheel surface are complex and typically require a number of discrete steps involving chemical deposition of multiple layers of metal onto the surface.
A typical method for chrome plating a wheel is illustrated in the flow chart shown in FIG. 1. In functional block 10, a formed wheel that has been machined to final shape is provided. As shown in block 11, the wheel is prepared for chrome plating by first immersing the wheel in a solvent bath. The solvent bath removes oils and dirt, which would inhibit adhesion of metal deposits to the wheel surface. The wheel, in functional block 12, is pretreated by immersion in a chemical bath to dissolve any surface oxides. This further improves the adhesion of metal deposits to the wheel surface. The wheel is then rinsed, as shown in functional block 13, by immersion in a water bath or spraying with a high pressure water jet. The preparatory steps of removing oil and dirt, dissolving surface oxides and flushing are typically referred to as cleaning the wheel surface.
The chrome plating process begins in functional block 14 with the immersion of the portion of the wheel to be chrome plated in a chemical bath containing nickel in solution. During immersion, a thin layer of nickel, referred to as a prenickel layer, is chemically deposited upon the wheel surface to enhance adhesion of successive metal layers thereto. This prenickel layer tends to have a relatively uneven surface. Accordingly, in functional block 15, a copper layer is chemically deposited, usually by immersion of the wheel surface in another chemical bath which contains copper in solution, over the prenickel layer. The copper layer fills in uneven portions of the prenickel layer, forming a smooth surface. To further enhance the surface smoothness, the copper layer is buffed, as shown in functional block 16. In functional block 17, a second nickel layer, referred to as a semibright nickel layer, is formed by chemical deposition over the buffed copper layer. The semibright nickel layer provides corrosion resistance. Next, in functional block 18, a layer of nickel containing sulfur is chemically deposited over the semibright nickel layer as a sacrificial corrosion layer. In functional block 19, a final bright nickel layer is deposited onto the surface to provide reflectivity and brightness to the wheel surface.
The layers of nickel and copper provide a base upon which the chromium layer is deposited. In functional block 20, a prechromium layer is deposited ever the bright nickel layer. This layer is formed from discontinuous chrome, or pixy dust, to provide a more durable surface layer. Finally, in functional block 21, a layer of chromium is deposited to prevent nickel fogging.
During the chrome plating process, each successive metal layer is typically formed by immersing the portion of the wheel surface to be chrome plated in a chemical bath containing a solution of the particular metal to be deposited on the wheel surface. Thus, each layer is chemically bonded to the preceding layer to provide a durable and attractive decorative surface coating on the wheel. Known methods for forming other types of wheel surface finishes are similar to the above described chrome plating process and typically include a number of discrete steps.
This invention relates to a surface finish for a light weight vehicle wheel and a process for forming the surface finish.
As explained above, it is desirable to apply an attractive and durable surface finish to vehicle wheels. One known method involves chrome plating the wheel however, as described above, the chrome plating process is complex, and hence time consuming and costly. Additionally, the many steps involved increase the potential for defects in the surface finish which would cause the wheel to be scrapped.
Accordingly, a simpler method for forming a decorative finish upon a vehicle wheel surface would be desirable.
The present invention contemplates a process for forming a finish upon a vehicle wheel which includes depositing a base layer formed from an organic material onto at least a portion of a surface of the vehicle wheel. The base layer of organic material is then cured. A first finish layer formed from a first inorganic material is deposited over the organic base layer and a second finish layer formed from a second inorganic material is deposited over the first inorganic layer. The invention also contemplates cleaning the surface of the wheel before depositing the base layer of organic material onto the wheel surface. The cleaning of the surface of wheel may form an optional intermediate layer of material between the surface of the wheel and the base layer of organic material.
It is further contemplated that the first inorganic layer can include a color. Additionally, or alternately, the first inorganic layer can include a metallic or a ceramic material while the second inorganic layer can include a ceramic; clear coat.
The invention also contemplates a vehicle wheel having an annular wheel rim and a circular wheel disc formed across an end of the wheel rim. A first layer formed from an organic material is disposed over at least a portion of a surface of either the wheel rim or the wheel disc. A second layer formed from a first inorganic material is disposed over the first layer formed from an organic material and a thin layer formed from a second inorganic material is disposed over the second layer formed from an inorganic material. The wheel may optionally include an intermediate layer disposed between the surface of the wheel and the first layer of organic material.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.